Go to Structure -> Blocks Here you can fill the information regarding a block like,

1. Block Title (you can override the default title for the block. Use to display no title, or leave blank to use the default block title. This field supports tokens.)
2. Region settings here you could specify in which themes and regions this block is displayed.
3. Visibility settings, here you can actually control the the Block visibility on pages, here you can define the pages where this BLock should appaer We have Option Tabs here
   1. Pages

   Under Pages tab you do have two option 1. All pages except those listed (if this is selected Block will appear on all pages of the site except the pages url defined in here.) 2. Only the listed page (if this is selected Block will appear only on the pages whose ulr is defeined here.)

   2. Content Types

   Show Block only on pages that display content of the given type(s). If you select no types, there will be no type-specific limitation.

   3. Roles

   Display Block only for the selected role(s). If you select no roles, the block will be visible to all users.

   4. Users

   Allow individual users to customize the visibility of this block in their account settings.